Double circuit hydraulic distributor



Jan. 13, 1959 J. FAISANDIER 2,868,217

DOUBLE cmcuzw HYDRAULIC DISTRIBUTOR Filed March 26, 1956 INVENT OR 2 JACQUES FAISANDIER Z ATTORNEYS United States Patent DOUBLE CIRCUITHYDRAULIC DISTRIBUTOR Jacques .Faisandier, Chatillon-sousfliagneux, France Application March26, 1956, Serial No. 573,800

Claims priority, application France March 29,1955

3 Claims. (11. 137-112 This invention relates generally to devices for distributing a liquid under pressure in hydraulic .control systems. ..In a hydraulic control system the risks ofdifficulties occurring are greater in the source of energy proper and the pipelines ratherthan in the receiver or pressure operated load itself. This is obvious in practice'when the pressure operated motor orload is .a jack (ora servocontrolled jack), which isa very simple and robust element, while the source of energy may consists of a pump, accumulators, hydraulicgovernors, feed-lines, and the like. From the .point of view of dependability it maybe necessary to duplicatethe energytransferring circuits to the pressure operatedmotor itself.

The invention has for its object a control arrangement which is adapted to be selectively connected to the normal circuit or to an emergencycircuit, which enables a pressure operated motor to be putinto the emergency circuit automatically when an accidental pressure drop occurs in the normal supply circuit.

The device comprises in principle three slide valves, subjected to the pressures .of the two circuits in such a manner that they are urged in opposite directions. A first slide valve is provided for distributing the pressure on the .end faces of the other twoslide valves, thefunctionof the other two slide valves being to changeover the supply circuits to the pressure operated motor or the distributor for the motor, and to change over the return circuits of the motor or of the motor distributor, to one reservoir or to the other reservoir, from which the working fluid can again be circulated by a pump in the usual way.

An exemplified embodiment of the invention is given hereinbelow without intending to limit the scope of the invention to the features shown or to features specific to the example chosen for illustration.

In the accompanying drawing:

Figure 1 shows a control arrangement in the condition of normal operation, and

Figure 2 shows the control arrangement in the condition of operation of the emergency circuit.

In a body designated by reference character 1 are disposed the following:

Reference characters P and B indicate the pressure supp-1y line and discharge pipe or passage, respectively, leading to the reservoir of the normal circuit; P and B indicate the pressure supply pipe and discharge pipe, respectively, leading to the reservoir of the emergency circuit.

Three slide valves are disposed in appropriate pas sages. T T form the distributing slide valve proper, and C, D are change-over slide valves.

The distributing slide valve consists of two symmetrical valve parts T and T having a series of pistons and which parts are joined by link 2 which carries a plate 3 to serve as a support for compression spring 4, adapted to urge the distributing slide valve to the right, as there shown. The spacebetween valve parts T and T cornmunicates with the atmosphere through orifice 21.

The piston P-T 1 of the valve part T may occupy different relative positions such that, in its--extreme righthand'position, it-connects supp-1y pipe P with thegduct 5 so as to cause pressure to act on the *left-handsurfaces of pistons PC and PD of the slide-valves C and D; and with theduct 6 connecting the passage 7 of the slide valve C,-while it cuts ofi duct 8, which communicates with the-passage 9 of the slide valve D.

Inits extremeright-hand position the slide valve '0 established communicationbetween the duct6. and orifice Uleading to the pressure operated motor M or other load, whileit cutsotf the right=hand-part of the'passage which is under pressure from the duct 22 by bearing heavily on its right-hand seat 10. The piston C with its plate 11 is subjected to the resilient action of the spring 12,-which prevents wobble.

The slide valve D, with its plate 13 and its spring 14, in its extreme right-hand-position, establishes communication between duct B, the orificeBthrough which the liquidreturnsfromthepressure operated motorM or other receiver to the discharge pipe B and cutsofl the right-hand part of the passageleading to the discharge pipeB and to the associated reservoir bybearingjheavily on its right-hand seat 15.

In view ofthe symmetryof theslide valves in relation to the axis ofthe line "XXL-it will beseen that the pistonPT of-the valve-part T in the extreme'right-hand position-allows the duct16-leading to the reservoirto communicate with the duct 22 which supplies the discharge pipe (l5 pressure to*the-right'hand surfaces of the pistons PC and IPDZ of the slide valves CandD andcuts oif the supply pipe P from the duct 22.

The movement of the distributing slide valve T T is of the order of-3-millimeters and is limited by the stops it? and 1%. Calibrated orifices T andfitl enable the end surfaces of theslide valve part T to remain under pressure and obviate vibration. These calibrated orifices could be -replaced by dash-pots or "by suitable clearances provided between the housings and the end pistons of the slide valve T T The operation of the device is as follows:

By the action of their respective springs the slide valves are normally in the extreme right-hand end position. As long as the liquid under pressure entering at P prevails on the left-hand surfaces of the pistons PT PC and PD the right-hand surfaces of the pistons PT PC PD are connected to the reservoir, through the pipes 22, 16 and discharge pipe B The Figure 1 position of the pistons is therefore a normal position when the liquid under pressure arrives at supply pipe P Under these conditions the fluid circuit is established through P duct 6, orifice U, pressure operated motor M, or other receiver, orifice B and discharge pipe B If the pressure from the normal circuit should fall or fail at P the liquid under pressure supplied by P and acting on the right-hand end surface of the piston PT of valve part T presses the valve part T to the left (Figure 2) against the action of spring 4, and as soon as the distributing slide valve has commenced its movement and has established communication between P and duct 22, the pressure acts on the right-hand surfaces of the pistons PC and PD the three slide valves are then moved to the left-hand position and a circuit is established through P duct 26, orifice U, pressure operated motor M, or other receiver, orifice B and discharge pipe B which thus forms an emergency circuit, the duct 5 being in communication with the reservoir through duct 8 and discharge pipe B What I claim is: 1. A hydraulic distributing device for automatic connection of a receiver into a normal or an emergency pressure comprising in combination, passage means .formed between each said source and said receiver respectively, a first common sliding distributing valve in each of said passage means, a second common sliding distributing valve in each of said passage means between the said first distributing valve and the receiver, a plurality of resilient means urging respectively said first distributing valve and said second distributing valve into positions whereby the passage is cleared in normal circuit condition between the normal supply source and said receiver when the pressure is the same in the two circuits, said resilient mean-s rated to let said valves slide into positions whereby the passage is cleared in the emergency circuit in response to a drop of pressure in the normal circuit.

2. A hydraulic distributing device for automatic connection of a receiver respectively with one of two sources of fluid pressure at equal pressure and with one of two discharges and preventing intermixture therebetween thereby forming a normal and an emergency circuit, comprising in combination a passage means formed between each of said pressure sources and the receiver and extending between the receiver and each of the discharges for respective normal and emergency flow, a first common sliding distributing valve interposed in the normal circuit and in the emergency circuit between the several sources and the receiver, a second common sliding distributing valve interposed in each of said normal and said emergency circuits between said first distributing Valve and the receiver, a third common sliding distributing valve interposed in each of said passage means between the receiver and the discharges respectively, a plurality of resilient means urging the three said distributing valves into respective positions in which the passage is clear in the normal circuit between the normal source and discharge and the passage is interrupted in the emergency circuit between the emergency source and the discharge when the pressure is the same in the two circuits, said resilient means rated to let the said valves slide in respective positions in which the passage is clear in the emergency circuit between the emergency source and discharge and the passage is interrupted in the normal circuit between the normal source and discharge in response to a drop of pressure in the normal supply.

3. A hydraulic distributing device for automatic connection of a receiver respectively with one of two sources of pressure fluid at the same pressure and with one of two discharges while preventing intermixture therebetween thereby forming a normal and an emergency circuit, comprising in combination a multiported longitudinally bored valve casing having two inlet ports and two outlet ports for the discharge, three longitudinal bores having three spool valves respectively sliding in said bores, a first passage means formed between each of said inlet ports and the extremity of the first bore, a pair of second passage means formed between said first bore and the respective extremities of the second and the third bores, said second passage means for normal fluid pressure passage and emergency fluid pressurepassage respectively, a third passage means between each of said inlet ports and its corresponding discharge through the three bores successively, the receiver being connected between the second and the third bore, a pair of by-pass passages formed between the first and the third bore, a plurality of resilient means urging each spool valve in respective positions in which the normal circuit is cleared and the emergency circuit interrupted, the normal pressure passage and the corresponding by pass passage being in communication through the first bore and the communication between the emergency pressure passage and its by-pass passage being interrupted in the first bore when the pressure is the same in both circuits, and rated to let the three valves slide into positions in which the above recited communications are reversed in response to a drop of pressure in the normal circuit.

Morrow July 12, 1927 Winchester Oct. 9, 1951 

